Work around offsetof quirk on Clang/libc++/Linux
Work around offsetof quirk on Clang/libc++/Linux

Resolves #519.

actor-framework/actor-framework,nq-ebaratte/actor-framework,DavadDi/actor-framework,DavadDi/actor-framework,nq-ebaratte/actor-framework,actor-framework/actor-framework,nq-ebaratte/actor-framework,actor-framework/actor-framework,DavadDi/actor-framework,DavadDi/actor-framework,nq-ebaratte/actor-framework,actor-framework/actor-framework